Conor Sims Jackson (born May 7, 1982) is an American former professional baseball first baseman and left fielder.

He played in Major League Baseball (MLB) between 2005 and 2011 for the Arizona Diamondbacks, Oakland Athletics, and Boston Red Sox.

His 2009 season was stalled in May when he contracted Valley Fever and lost approximately 35 pounds during the illness (per his interview on Chronicle Live 6/21/10).

[5] After the demotion of Daric Barton in the spring of 2011, Jackson saw the majority of his starts at first-base until the call-up of trade acquisition Brandon Allen.

Jackson would only play in 18 games for the A's that year and only 60 for the entire season, finishing with a .236 batting average 2 home runs and 16 RBI.

[6] On September 19, he hit his first home run in a Red Sox uniform, a grand slam over the "Green Monster" at Fenway Park, in an 18–9 rout of the Baltimore Orioles.

On March 31, 2012, Jackson signed a minor league deal with the Chicago White Sox, and was assigned to Triple-A Charlotte.

[9] On December 5, 2012, Jackson was signed to a minor league deal with the Baltimore Orioles that included a spring training invitation.